1. Field of the Invention
This invention relates generally to a vehicular seat which is adjustable in position forward and rearward of a vehicle body, and more particularly to improvements in a vehicle seat to improve a vehicle passenger's riding comfort and prevent the generation of foreign noises.
2. Description of the Prior Art
It is well known that a seat cushion of a vehicular seat is adjustably movable forward and rearward of a vehicle body. In order to facilitate adjustable movement of the seat cushion, it has been proposed and put into practical use that a seat back hingedly connected with the seat cushion is divided into upper and lower seat backs as shown in FIGS. 7 and 8 of the present application. Such an arrangement is disclosed, for example, in Japanese Utility Model Publication Nos. 57-11580 and 60-31547.
As shown in FIGS. 7 and 8, a seat cushion 1' is adjustably movable forward and rearward of a vehicle along a slide 5' on the floor of the vehicle. A seat back 2' includes upper and lower seat backs 6', 7'. The lower seat back 7' is hingedly connected at its lower end section to the rear end section of the seat cushion 1 through a hinge pin 4', and hingedly connected at its upper end section with the lower end section of the upper seat back 6' through a hinge pin 3'. The upper seat back 6' is slidably connected to a back panel of a vehicle body in a manner to move generally vertical along a guide opening of an adjuster.
In the thus arranged conventional vehicular seat, when the seat cushion 1' is moved forward, the lower seat back 7' is moved forward from a position shown in FIG. 7 to another position shown in FIG. 8, accompanied by movement of the upper seat back 6' in a direction indicated by an arrow. Thus, the lower seat back 7' effectively supports the waist of the vehicle passenger.
However, in such a conventional vehicular seat, the lower seat back is connected with the seat cushion and the upper seat back only through hinges including the hinge pins, so that no secure support is made for lower seat back. As a result, foreign noise is generated at the hinges of the lower seat back because of play or clearance in the hinges, thereby lowering the commercial value of the vehicular seat.
Additionally, Japanese Utility Model Publication No. 45-32323 discloses a vehicular seat of an arm chair type wherein a seat back is divided into upper and lower seat backs. More specifically, a connection shaft between the upper and lower seat backs is provided at a support box for chair arms. The lower seat back is changed in inclination in accordance with the forward and rearward movement of the seat cushion, while the lower seat back is not changed in location and inclination. Accordingly, such a vehicular seat cannot correspond to the postural change of the vehicle passenger.